Suprapubic catheterization of the bladder is used to drain the bladder after surgery or when the genitourinary system is plugged by an obstruction. Other percutaneously inserted catheters are also used to drain the kidney or biliary system as well as to drain abscesses, other sites of fluid collection, and other viscera. Still other percutaneously inserted catheters are gastrostomy feeding tubes.
These catheters are typically introduced into the patient by means of a large hypodermic needle or trocar, which pierces the abdominal wall. A wire guide is inserted through the needle and then removed. The catheter tube with a stiffening cannula positioned therein is then passed over the wire guide into the cavity. The cannula and wire guide are withdrawn, leaving the catheter in the desired cavity. With respect to the bladder, the advantage of this technique is that irrigation and infection of the urinary tract is minimized. However, one problem with these catheters is that the catheter can be easily pulled out by movement of the body or by the emptying of, for example, the bladder. Another problem is that side ports at the distal end of the catheter may be inadvertently drawn into the abdominal cavity, creating the potential for severe infections.
Various catheters have been developed with so-called pigtail loops at their distal ends for ensuring drainage of the cavity and preventing accidental removal therefrom. The pigtail loop is tightened by pulling on the proximal end of a flexible tension member, which extends through the catheter. The proximal end of this tension member is held in place by any one of a number of retention means. In one case, the proximal end of the flexible tension member is held in place by axially placing a hollow cap into or over the proximal end of the catheter tube, thus trapping the flexible tension member of which the protruding end may then be cut. A problem with this catheter design is that once the protruding end of the flexible tension member is cut, the hollow cap may slip or be inadvertently removed. As a result, the shortened flexible tension member moves distally, releases the pigtail, and is either difficult or impossible to retrieve.
In another case, the flexible tension member is trapped between two or more hollow tubes, one of which is slidably inserted axially into the other. A short length of the flexible member is generally left hanging from the catheter tube so that if the flexible tension member becomes loose, it may be retightened. Alternatively, an external sleeve is slid over the flexible tension member protruding from the side of the catheter tube of which the flexible tension member is then wound around and tied about the sleeve.
Although well-suited for its intended purpose, this catheter design leaves the flexible tension member exposed at the proximal end of the catheter. As a result, a physician must grasp and pull on the flexible tension member to secure or tie it about the proximal catheter end. In addition, a patient can untie the exposed flexible tension member and require the assistance of hospital personnel to retie the member. Furthermore, when the flexible tension member is inadvertently released, the retaining loop at the distal end is released with the possibility of the catheter being withdrawn from the patient.
In yet another case, the proximal end of a flexible tension member is bent and secured between two cooperating locking members, one of which is laterally movable across the path of the flexible tension member. A problem with this catheter design is that the locking members bend or deform the flexible tension member. As a result, the locking members may break or cut the flexible tension member, thereby inadvertently releasing the distally positioned loop and allowing the withdrawal of the catheter from the patient.